Nannies don't need a precedent, or scientific facts... for example...
Global Warming Climate Change ($$ and "control" drives that one, not common sense)
VA banned charity car-washes (because Chlorine might get into the water-table)
CT banned whole milk for day-cares (because it will stop obesity in children)
MT lawmaker is attempting to ban yoga-pants, short-skirts, and men's exposed nipples (because he doesn't like to look at them, poses 5-yr prison sentence for 3-strike 'wardrobe offense', which is better than the current 'life-sentence' )
MD bans Vaportinis (because you should drink your alcohol, not vape it, and one legislator thinks it "looks unsafe")
MN spends tens of thousands of tax dollars to put up signs "Feral cat colonies are prohibited on federal property" (because cats can read apparently, and always do what they are told)
MO bans mothers from breastfeeding near public pools (for sanitary reasons, despite allowing dogs to swim in public pools)
VA dept of education bans lip balm (carry or use) in the school (because someone in CA might be allergic to beeswax, and apparently lip-balm has been known to attack unsuspecting teens in the hallways... I'm sure they have video proof...)
and the best of the past year... FDA classifies sunscreen as a "drug", and refuses to approve ingredients used in Europe and Asia (since 1997, because sunscreen is classified as a 'cosmetic' everywhere but in the US) as "safe", and therefore renders our current sunscreen market horribly ineffective at blocking UVa, UVb, and UVc, compared to products you can buy anywhere else in the world (for pennies compared to US products)!